North Korea said on Saturday its nuclear weapons are not meant for negotiations but are intended for combat use against enemies that threaten its people and world peace, its state media reported.

On Tuesday, U.S. President Donald Trump restored his "maximum pressure" campaign on Iran, that includes efforts to drive its oil exports down to zero in order to stop Tehran from obtaining a nuclear weapon.

North Korean leader Kim Jong Un has vowed to bolster his nuclear weapons program in response to the U.S.’s enhanced security partnership with South Korea and Japan. Last year, the U.S. expanded bilateral military exercises with South Korean and trilateral training with South Korea and Japan.